[vox-tech] Secure Wiping hard drives

[Harold Lee]

There are a bunch of secure delete programs that one-up dd by
overwriting the file many times, asking the OS to sync the changes to
disk immediately, etc.

srm, wipe, shred and diskscrub documentation all reference a paper by
Peter Gutmann: "Secure Deletion of Data from Magnetic and Solid-State
Memory" (http://static.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/).

wipe (http://lambda-diode.com/software/wipe) seems to overwrite the
disk 34 times with different bit patterns. srm defaults to 35 passes.

Harold

On Fri, May 11, 2012 at 4:07 PM, Brian Lavender <brian at brie.com> wrote:
> Perhaps dd from /dev/zero is the solution for this problem? Wikipedia
> makes reference to a SpringerLink publication. See below for both.
>
> http://en.wikipedia.org/wiki/Dd_%28Unix%29#Disk_wipe
>
> Wright, Craig; Dave Kleiman2, and Shyaam Sundhar R.S. (2008). "Overwriting
> Hard Drive Data: The Great Wiping Controversy". Lecture
> Notes in Computer Science. Information Systems Security 5352:
> 243.257. doi:10.1007/978-3-540-89862-7_21. Retrieved 7 March 2012.
>
>
>
>
> On Fri, May 11, 2012 at 03:47:39PM -0700, Norm Matloff wrote:
>> Zeroing out all bytes gives some level of security, but is not enough
>> against a truly determined adversary who has lots of resources,
>> according to what I've read.
>>
>> A disk drive, being a mechanical device, will write to a slightly
>> different physical spot each time it writes to a particular bit position
>> on the disk.  Sophisticated sensing mechanisms may thus be able to
>> determine what had been stored in that bit before a 0 was written to it.
>>
>> For that reason, the more sophisticated shredding utilities do more than
>> merely write 0s; they will do so multiple times.
>>
>> Norm Matloff
>>
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>
> --
> Brian Lavender
> http://www.brie.com/brian/
>
> "There are two ways of constructing a software design. One way is to
> make it so simple that there are obviously no deficiencies. And the other
> way is to make it so complicated that there are no obvious deficiencies."
>
> Professor C. A. R. Hoare
> The 1980 Turing award lecture
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